If you are a Small Business customer, find additional troubleshooting and learning resources at the Support for Small Business site.

A server that is running Microsoft Forefront Threat Management Gateway (TMG) 2010 may stop accepting new connections on a specific web proxy or web listener. This problem may occur after several hours to several days of server uptime.

This problem occurs when TMG stops accepting new connections on the web listener. This soon fills the backlog queue for the ancillary function driver (AFD) socket. After the backlog queue is full, the server starts to reset new incoming connections. If you monitor the server by using Network Monitor in this situation, you may notice a SYN, ACK/RST pattern for each new connection attempt.